Unfortunately, we just let you manage one event (you know, the big event) for now.
We suggest that you add "Questions to Guests" on your website RSVP page, and ask guests if they are attending other wedding-related events you're holding. We have some suggested questions like "Will you be attending the Morning-After Brunch?" that you can customize however want.
We are working on supporting multiple-event RSVPs soon, so check back shortly.